Hydrazine as an anti-staining agent for a peroxide bleaching solution



4 Claims. 61. 8111) ABSTRACT OF THE DISCLOSURE Method of preventing so-called catalyst injury of textiles during bleachingwitli' peroxidic bleaching agents engendered by presence of iron or iron alloy particles in such textiles which comprises treating such textiles with a hydrazine compound such as hydrazine hydrate and hydrazine salts before or during such bleaching.

The present invention relates to a method of preventing so-called catalyst injury of textiles during bleaching with peroxidic bleaching agfl ts engendered by the presence of iron or iron alloy particles.

It is known that the presence of even small particles of ,1ron or iron alloys during the bleaching of textiles with peroxidic bleaching agents cause so-called catalyst injuriesFib'eF-injuries occur in the neighborhood of the iron particles which ca the yarns to become more or less weakened depending updirthe particular conditions concerned or become completely fragile. In woven fabrics holes can form at the injured locations.

One of the main sources of the presence of iron dust during bleaching is the grinding dust formed during the grinding of the steel needs of the carding machines or during grinding of the drums of such machines. However, ironfrom other sources can also reach thebleaching apparatus. 5.

It-was unexpectedly found that the occurrence 9 "so ing of fibers, yarns, woven fabrics, knitted fabrics and textile goods, especially those of cellulose or containing cellulose, with aqueous bleaching liquors containing peroxidic bleaching agents, when bleaching liquors are employed which contain additions of hydrazine, hydrazine hydrate or its salts, hexitols, such as, sorbitol, alkali metal or ammonium acetate or alkali metal or ammonium chromate or bichromate, either individually or in admixture. When peroxidic bleaching liquors containing such substances are employed in the presence of iron and steel particles catalytic injury only occurs to a very slight extent or is completely prevented.

Only very small quantities of such additional substances suffice to achieve the desired eifectfIn general, with the addition of hydrazine or its compounds 0.025 to 0.25 g. per

liter of bleaching liquor sufiiceAs a rule, 1 to 3 g. of the hexitols or 1 to 5 g. of theacetates per liter of bleaching'liquor suflice. In the -case of the chromates and bichromates, additions of only 0.05 to'.1 g. per liter suflice.

In many instances it sufiices if the additional substances are not added to the bleaching liquors themselves but rather to the pretreating liquors which, for example, are used for desizing, wetting, washing and the like.

The peroxidic compounds employed in the preparation of peroxidic bleaching liquors are those usually'employed, such as, for example, hydrogen peroxide, soduim peroxide, other alkali metal or alkaline earth metal peroxides, persulfuric acid or its salts, perboric acid or its salts, percarbonic acid or its salts, perphosphoric acid, or its salts United ,States Patent 3,348,903 Patented Oct. 24, 1967 or similar compounds which form hydrogen peroxide in an aqueous acidmedium. Such peroxidic bleaching compounds, for example, can be employed in such quantities as to provide 0.5 to 7.0 g. of active oxygen per liter of bleaching bath.

The following example will serve to illustrate the indiastase), 1 g. NaCl and 1 g. hydrazine hydrate (24%) per liter and-heldin such solution at 55 C. over night.

As a control, alfurther 100 g. sample of thesame fabric was desized in' the same manner except that the hydrazine hydrate was omitted from the desizing solution.

On the next day both samples were taken out of the desizing solutions, squeezed out and thoroughly washed with water. The iron dust associated with the fabric which was desized in the solution containing the hydrazine hydrate showed no rusting phenomena whereas that associated with the fabric which was desized in the solution from which the hydrazine hydrate was omitted was strongly rusted.

Both samples were then given a peroxide bleaching by the impregnating-steaming process in which such samples were, first impregnated with an aqueous bleaching liquor containing 33 cc. Water glass 38/40' B., 8 g. of solid caustic soda, 35. cc. H 0 (35% by weight) and 2 g. of sodium dodecyl benzene sulfonate per liter, then squeezed out to 100% moisture content, and rolled flat on a glass tube and steamed in this condition at about -100 C. by direct supply of steam thereto for 2 hours. After such bleach the samples were rinsed with water. A good bleaching effect was achieved and they were completely free from seedlshells. Neither rust formation nor catalytic injury \i afiebserved on the bleached sample which had been de- I sized-with the solution containing the hydrazine hydrate, called catalytic injury can be prevented during the bleach wher 'eas the bleached sample which had been desized without the addition of hydrazine hydrate exhibited strong rust formation at the spots to which the iron dust had adhered and also exhibited catalytic injury to the fibers which in some instances led to the formation of holes.

I claim:

1. In a process for bleaching textile fabrics with aqueous peroxidic bleaching liquors which fabrics have ferrous metal particles therein likely to cause catalytic injury to such fabrics during the bleaching with the aqueous peroxidic bleaching liquor, the step of treating said fabrics with at least one hydrazine compound selected from the group consisting of hydrazine hydrate and hydrazine salts in an aqueous medium at a point not later than said bleaching process with the aqueous peroxidic bleaching liquor, the amount of said hydrazine compound employed in said treatment being sufiicient to prevent any catalytic injury to the fabrics caused by said presence of ferrous metal particles.

2. The process of claim 1 in which said textile fabrics are cellulosic.

3. The process of claim 1 in which the fabrics to be bleached are pretreated with at least one of said compounds.

4. In a process for bleaching textile fabrics with aqueous peroxidic bleaching liquors which fabrics have ferrous metal particles therein likely to cause catalytic injury to such fabrics during the bleaching with the aqueous peroxidic bleaching liquor, the step of treating said fabrics in an aqueous liquor containing about 0.02 g. to 0.25 g.

3,348,903 3 4 per liter of hydrazine hydrate prior to such bleaching to FOREIGN PATENTS prevent any catalytlc m ury to the fabrics caused by said 8/1960 Great Britain.

presence of ferrous metal particles. 846079 References Cited 5 UNITED STATES PATENTS 11/1963 Doerr 8108.5

J. H. RAUBITSCHEK, Assistant Examiner.

NORMAN G. TORCHIN, Primary Examiner. 

1. IN A PROCESS FOR BLEACHING TEXTILE FABRICS WITH AQUEOUS PEROXIDIC BLEACHING LIQUORS WHICH FABRICS HAVE FERROUS METAL PARTICLES THEREIN LIKELY TO CAUSE CATALYTIC INJURY TO SUCH FABRICS DURING THE BLEACHING WITH THE AQUEOUS PEROXIDIC BLEACHING LIQUOR, THE STEP OF TREATING SAID FABRICS WITH AT LEAST ONE HYDRAZINE COMPOUND SELECTED FROM THE GROUP CONSISTING OF HYDRAZINE HYDRATE AND HYDRAZINE SALTS IN AN AQUEOUS MEDIUM AT A POINT NOT LATER THAN SAID BLEACHING PROCESS WITH THE AQUEOUS PEROXIDIC BLEACHING LIQUOR, THE AMOUNT OF SAID HYDRAZINE COMPOUND EMPLOYED IN SAID TREATMENT BEING SUFFICIENT TO PREVENT ANY CATALYTIC INJURY TO THE FABRICS CAUSED BY SAID PRESENCE OF FERROUS METAL PARTICLES. 